Telephone-transmitter



(No Model.)

N. BOWLING.

TELEPHONE TRANSMITTER. No. 335,511. Patented Feb. 2, 1886.

WITNESSES:

UNITED STATES PATENT OFFICE.

NORTH DOIVLING, OF PHILADELPHIA, PENNSYLVANIA.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 335,511, dated February 2, 1886,

Application filed February 14, 1885. Serial No. 155,925.

To all whom it may concern:

Be it known that I, NORTH DOWLING, a citizen of the United States, residing in the city and county of Philadelphia, and State of Pennsylvania, have invented certain new and useful Improvements in Telephone-Transmitters, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings.

This invention relates, generall y,to i mprovement-sin the class of telephone-transmitters of which the Blake transmitter is an example. It is a modificatiomin certain respects, of an improvement in transmitters of the said class for which I filed an application for Letters Patent February 1i, 1885, Serial No. 155,- 924, and I hereby disclaim all devices embraced in the present application which are claimed in said above-mentioned application. In the latter device I relied solely upon the force of gravity to regulate the contact between the carbon button and the platinum bead of the diaphragm-plate. In the presentinstance I use an adjustable magnet in connection with a carbon-bearing arm or pivoted lever for regulating the carbon-platinum contact.

I shall now proceed to describe one mode, the best that has occurred to me, of carrying out the invention, reference being had to the annexed drawings, of which- Figure l is a front elevation of the transmitter-box, looking into the same, the lid or doorhaving been thrown open. Fig. 2 is a section, enlarged, as on line a I), Fig 1, with the lid closed. Fig. 3 is a section as on line cd, Fig. 1, looking in the direction of the adjacent arrow.

A is the transmitter'boxflo the inside of the lid B of which is secured the diaphragm-plate C,with the platinum bead D, Figs. 2 and 3, secured by a disk,x,fastened to the diaphragm, and of usual construction.

E E are the respective arms of a bell-crank lever, which is nicely pivoted upon trunnions or cones F, Fig. 3, whose points enter sockets in the ends of two opposite adjusting-screws, G, Figs. 1 and 3, that pass through holes in flanges h of a plate, I, that is connected with one of the wires w leading to the usual battery. (Not shown.) Arm E extends over the dia- (No model.)

phragm C, and bears at or nearitsfree end, over theplatinum bead D, a carbon sleeve or button, J. The other wire, 10, of the battery-circuit connects the platinum bead with the primary coil of the helix K,contained within the transmitter-box, and the wires 10 of the secondary of the inductorium connected with theline as usual.

Thus far the construction is similar to that of my gravity-regulator described in the application to be made for a patent hereinbefore referred to; in fact, the present device requires but an adjustable counterpoise in lieu of the magnet hereinafter mentioned, to be applied to the arm E, to be identical therewith. I substitute,however, for the said counterpoise, a magnet, M, permanent or electro, which, in the present instance, is a horseshoemagnet. This is secured loosely to theinside of the bottom of the transmitter-box by means of straps Z, so as to allow it (the magnet) to he slid to and fro. The position of the latter, as shown,is such that its ends or poles, which are substantially at right angles to the arm E when the door is closed, (see Fig. 2,) may be brought in proximity with the latter. It will of course be understood that this arm E is of iron,in order to constitute an armature to the magnet. flattened wire with its free end bent into a rectangular loop, as 0, so as to extend across the field of the poles of the magnet.

As a means of adjusting the magnet to and from the arm E, I employ in connection with the former a screw, N, that works in a threaded box, P, fixed on the lower side of the transmitter-box. When the button 1 on the outside is turned,the magnet is forced forward or retracted, as required.

The operation of the device is apparent, as it is quite obvious that the nearer the poles of the magnet are brought toward the loop of the pivoted bell-crank arm E the more strongly will the latter be drawn to the magnet, and consequently the greater the pressure of the carbon button at the end of the other arm, E, of the bell-crank against the platinum point, and the converse. The springy bears lightly against the arm E, and while it does not hold the contact-point away from the diaphragm it prevents the arm from vibrating too violently,

I prefer to make the same of and thus producinga rattling noise atrthe re carbon-bearing lever, the whole arranged as ceiver, which would interfere with distinct) described, whereby the mechanism may be articulation. accurately adjusted, substantially as specified. What I claim, and desire to secure by Let- In testimony whereof I have hereunto afters Patent, isfixed my signature this 17th day of January, 1

The c'0mbinati0n,in a telephone-transmitter, A. D. 1885. V of the diaphragm and platinum point, the NORTH BOWLING. carbon-bearing lever, and the armature-arm, Witnesses: A the permanent sliding magnet and adj u sting- JOHN NOLAN, 7 screw, and. the flat spring bearing against the FRANCIS S. BROWN. 

